Question

I have a 43 year-old asymptomatic white male with a multinodular goiter and a 3.1 cm dominant nodule on the right thyroid lobe diagnosed in 11/2005. He has no family history of thyroid cancer and no history of head and neck radiation exposure. Thyroid function tests within normal limits. A subsequent FNA revealed a follicular lesion with the differential of a hyperplastic thyroid nodule vs. a neoplasm. The patient opted for a total thyroidectomy in 2/2006 and the subsequent pathology report revealed a 3 cm microfollicular adenoma but there was an incidental finding of a 4 mm papillary microcarcinoma of the left lobe. He did not undergo RAI and his previous doctor just put him on suppressive doses of levothyroxine. He established himself with me after having moved to the area and he is presently on 150 mcg of levothyroxine daily and his latest TSH of 11/21/2006 is 0.86. He denies any symptoms. A thyroid US of 10/2006 revealed no thyroid tissue or mass in the thyroid bed area. There is excellent evidence in the existing literature that says that microcarcinomas have excellent prognosis. My question pertains to the appropriate follow up of these patients. I plan to do thyroglobulin and thyroglobulin antibody levels every six months and to continue suppressing his TSH levels to <1 UIU/ML. Unfortunately, I have no previous thyroglobulin levels. I am also planning to do a thyrogen scan and metastatic search in 2/2007 a year from the original diagnosis.

If his thyroglobulin levels are detectable (>2 ng/ml) and there is evidence of residual thyroid tissue on the thyrogen scan, then is the treatment similar to macropapillary carcinomas? I know of some colleagues who treat micropapillary carcinomas as if they were larger tumors (30 mCi ablative dose post-op, thyroglobulin levels every 6 months, thyrogen scans yearly, and if positive to do higher ablative dose of RAI) and I am wondering if this a more appropriate surveillance option.

Patrick Litonjua, MD Binghamton, NY

Response

The usual thought is that an incidentally resected <1cm papillary ca found at operation for a MNG requires no specific follow-up for the cancer. Your patient had a complete surgical resection, a negative US, and is on T4 with a bottom-normal TSH. Certainly following his TG at intervals (? 1yr) is an easy added safety check. If it should climb, US would be very appropriate. I think most therapists would not consider 131-I ablation, rhTSH-TG testing, or scanning, to be needed in this instance.